Currently, an electrical connector for electrically connecting a chip module to a circuit board in the prior art includes an insulating body, a plurality of signal terminal slots formed through the insulating body, wherein a shielding layer is disposed in the signal terminal slot, a recessed portion is disposed at a bottom surface of the insulating body, and the recessed portion has a metal layer electrically conducted with the shielding layer, a plurality of signal terminals, respectively accommodated in the signal terminal slots, a grounding sheet, accommodated in the recessed portion, wherein a part of the grounding sheet located in the recessed portion is in full contact with an inner wall of the recessed portion, and a plurality of solder balls, wherein one of the solder balls is securely mounted on the grounding sheet, and the grounding sheet and the circuit board are soldered and conducted.
The grounding sheet is placed in the recessed portion. In order to prevent the grounding sheet from falling off from the recessed portion due to gravity and vibration during transportation, it is a common method to increase the contact area of the grounding sheet and the recessed portion, wherein the part of the grounding sheet located in the recessed portion needs to be in full contact with the inner wall of the recessed portion.
However, the above method incurs the following problems.
When the solder ball is soldered, when the electrical connector generates heat during operation, or when the electrical connector is in an environment of extreme temperature, both the insulating body and the circuit board undergo expansion. As the material of the insulating body and the material of the circuit board have different expansion coefficients, the insulating body and the circuit board undergo different degrees of expansion. Therefore, the recessed portion disposed on the bottom surface of the insulating body is displaced relative to the circuit board, and accordingly the grounding sheet accommodated in the recessed portion and the solder ball disposed corresponding to the grounding sheet are displaced relative to the circuit board, thus the solder ball is displaced relative to the corresponding solder joint on the circuit board, which causes a solder cracking phenomenon.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.